Mist extraction system

ABSTRACT

A mist extraction system is provided that includes a plenum box having an inlet configured to be coupled in fluid communication with a machine tool enclosure. A blower is coupled in fluid communication with the plenum box and is configured to draw air into the plenum box from the machine tool enclosure via the inlet of the plenum box and exhaust the air back into the machine tool enclosure via an outlet of the blower. A baffle plate is arranged in the plenum box to redirect the air drawn into the plenum box through the inlet of the plenum box and a filter panel is arranged in the plenum box to filter the air redirected by the baffle plate prior to the air entering the blower. A collector arranged to collect mist from the air condensed on the baffle plate and the filter panel.

CROSS-REFERENCE TO RELATED APPLICATION

The application is a continuation application of U.S. patent applicationSer. No. 16/557,633, filed on Aug. 30, 2019, which claims the benefit ofU.S. Provisional Application No. 62/725,191 titled “MIST EXTRACTIONSYSTEM” and filed on Aug. 30, 2018, the disclosure of each of which isincorporated by reference herein.

TECHNICAL FIELD

The subject disclosure generally relates to machine tools and, moreparticularly, relates to the extraction of mist generated during cuttingoperations of computer numerical control (CNC) machine tools.

BACKGROUND OF THE DISCLOSURE

CNC machine tools may utilize cutting tools such as, for example, taps,drills and boring bars, that require lubrication to prevent heatbuild-up and premature wear. To optimize the efficiency of a CNC machinetool, the amount of lubricant or cutting fluid applied to the cuttingtool during operation may be minimized, which may be described as “neardry machining.” One approach to near dry machining is to direct mistedor atomized lubricant at the cutting tool during operation. However,this approach results in the suspension of lubricant particles in mistsin the air surrounding the cutting tool. Similarly, during wet machiningin which a liquid coolant is directed at the cutting tool duringoperation, the liquid coolant may be atomized when hitting the cuttingtool at high speeds resulting in the suspension of the liquid coolant inmists in the air surrounding the cutting tool. These mists can bedeleterious to machine tool operators' health and may leave anundesirable residue on the workpiece and other surfaces exposed to themist.

The description provided in the background section should not be assumedto be prior art merely because it is mentioned in or associated with thebackground section. The background section may include information thatdescribes one or more aspects of the subject technology.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating components of a CNC machine toolaccording to aspects of the subject technology.

FIG. 2 is a block diagram illustrating a process flow during operationof a mist extraction system according to aspects of the subjecttechnology.

FIG. 3 is a side view of filter assembly 52 with partial transparency toillustrate interior components according to aspects of the subjecttechnology.

FIG. 4 is a cross-sectioned view of a filter assembly according toaspects of the subject technology.

FIG. 5 is a perspective view of a filter assembly according to aspectsof the subject technology.

FIGS. 6A and 6B illustrate a return register according to aspects of thesubject technology.

In one or more implementations, not all of the depicted components ineach figure may be required, and one or more implementations may includeadditional components not shown in a figure. Variations in thearrangement and type of the components may be made without departingfrom the scope of the subject disclosure. Additional components,different components, or fewer components may be utilized within thescope of the subject disclosure.

DETAILED DESCRIPTION

The detailed description set forth below is intended as a description ofvarious implementations and is not intended to represent the onlyimplementations in which the subject technology may be practiced. Asthose skilled in the art would realize, the described implementationsmay be modified in various different ways, all without departing fromthe scope of the present disclosure. Accordingly, the drawings anddescription are to be regarded as illustrative in nature and notrestrictive.

FIG. 1 is a diagram illustrating components of CNC machine tool 10according to aspects of the subject technology. As illustrated in FIG.1, machine tool 10 includes control system 20, head unit 30, cuttingtool 35, machine tool enclosure 40, mist extraction system 50, and fluiddelivery system 60. Machine tool 10 represents one example of a CNCmachine tool. The subject technology is not limited to the type of CNCmachine tool depicted in FIG. 1 and may be incorporated into other typesor configurations of machine tools that may include differentcombinations and/or arrangements of components.

Control system 20 controls operations performed by components of machinetool 10. Control system 20 may include one or more processors, volatilememory (e.g., random access memory (RAM), static random access memory(SRAM), etc.), non-volatile storage devices (e.g., magnetic media,optical media, flash memory, etc.), a user interface, and a machineinterface. The processors may be configured to executes programs or setsof instructions stored in volatile memory and/or the non-volatilestorage devices to operate the components of machine tool 10 and performoperations described herein. A machine tool operator may monitor theoperation of machine tool 10, select or input sets of instructions forexecution, and/or manually control operation of machine tool 10 usingthe user interface. Control system 20 communications commands andreceives feedback information from other components within machine tool10 via the machine interface.

Head unit 30 may include one or more drive units (e.g., motors,spindles, actuators, etc.) for rotating and/or positioning cutting tool35 relative to a workpiece situated within machine tool enclosure 40 toremove material from the workpiece according to instructions receivedfrom control system 20. In other types of machine tools, such as alathe, the workpiece may be rotated relative to the cutting tool whereinmaterial is removed from the workpiece by positioning the cutting toolrelative to the spinning workpiece according to instructions receivedfrom control system 20. Machine tool enclosure 40 provides an enclosedspace to operate the cutting tool 35 and remove material from theworkpiece and prevent the scattering of debris out of machine tool 10.Machine tool enclosure 40 may include one or more doors to allow amachine tool operator to access the inside of machine tool enclosure 40to position or remove workpieces, access cutting tool 35, and/or cleanthe inside of machine tool enclosure 40.

Fluid delivery system 60 is configured to supply a cutting fluid to thepoint of contact between cutting tool 35 and the workpiece while cuttingtool 35 is being driven to remove material from the workpiece. Thecutting fluid is directed to the point of contact to both cool and cleancutting tool 35 and the surface of the workpiece. Fluid delivery system60 may include a storage tank for storing the cutting fluid, one or morepumps for delivering the cutting fluid from the storage tank to thepoint of contact through one or more nozzles. Fluid delivery system 60may be configured to collect the cutting fluid accumulated on the floorof machine tool enclosure 40 during operation of machine tool 10 andreturn the cutting fluid to the storage tank. A filter may be used toremove debris from the accumulated cutting fluid prior to returning thecutting fluid to the storage tank.

A machine tool operator may be exposed to contaminated breathing airwhen operating machine tool 10. The source of the contaminated air maybe the result of the cutting fluid used to lubricate and cool cuttingtool 35 while in contact with the workpiece. The collision of cuttingtool 35 with the cutting fluid and the workpiece may cause the cuttingfluid to heat up and atomize into small droplets called mist. Mist tendsto be lighter than air due to its thermal energy and therefore envelopesthe interior of machine tool enclosure 40. Upon program completion bymachine tool 10, the mist may remain present within machine toolenclosure 40 and when the doors of machine tool enclosure 40 are opened,by the machine tool operator, the mist may loft out of the machine justas the machine tool operator is reaching in to remove the finishedworkpiece from a work holding fixture or vise and be inhaled by themachine tool operator. In addition to the machine tool operator, themist may also loft into the breathing air of the entire facilityreaching others working within the facility

As used herein, the term “mist” refers to liquid droplets suspended inair. The airborne liquid droplets may be 20 microns in diameter orsmaller. Different types of cutting fluids may generate different sizesof liquid droplets suspended in the air. For example, water-solublecoolants may create mist droplets in the size range of 2-20 microns.Oil-based coolants may create mist droplets in the size range of 0.5-10microns. Oil smoke particles may be in the size range of 0.07-1.0microns. Inhalation of the mist by a machine tool operator or othersworking around the machine tool may be detrimental to their health.

Mist extraction system 50 is configured to remove mist from the airwithin machine tool enclosure 40 to reduce or remove exposure to themist by the machine tool operator and others in proximity to machinetool 10. FIG. 2 is a block diagram illustrating the process flow duringoperation of mist extraction system 50 according to aspects of thesubject technology. As depicted in FIG. 2, mist extraction system 50includes filter assembly 52, exhaust duct 54, and return register 56.The subject technology is not limited to this configuration or numbersof respective components. For example, multiple filter assemblies and/ormultiple return registers may be used according to aspects of thesubject technology. Briefly, mist-laden air is drawn into filterassembly 52 in which a filtration process is used to remove mist fromthe air. Following the filtration process, the filtered air is exhaustedfrom filter assembly 52 through exhaust duct 54 and returned to machinetool enclosure 40 via return register 56. While FIGS. 1 and 2 depictcomponents of mist extraction system 50 being arranged outside ofmachine tool enclosure 40, one or more components may be arranged withinmachine tool enclosure 40 according to aspects of the subjecttechnology.

Rather than attempting to remove the mist from the air in a single cycleand discharge the filtered air into the work environment like manyconventional mist extraction systems, the subject technologyrecirculates the filtered air back into machine tool enclosure 40 whereit reenters the filtration process of mist extraction system 50. Thisfiltration process and recirculation may continue beyond the end of acutting operation by cutting tool 35 based on control signals fromcontrol system 20. Accordingly, even when the cutting operation andtherefore mist generation ends, the recirculation and filtration processmay continue to further reduce the mist concentration level in the air.The mist concentration level may be detected directly using one or moresensors or inferred from known parameters of the system, such asperformance characteristics and run time. Various factors may affect thefiltration process and be factored into detecting or inferring the mistconcentration levels. For example, the application, size, type, andamount of mist droplets being generated, the internal volume of themachine tool enclosure, the size and number of air gaps in the machinetool enclosure, the area of the door of the machine tool enclosure, anair flow rate of air being extracted from the machine tool enclosure,concentration ratio of the cutting fluid, ambient temperature, humidity,and due point. The filtration process and recirculation may continue torun a predetermined period of time after the end of the cutting

operation or until the detected or inferred mist concentration levelshave reached a predetermined level. The filtration process performedwithin filter assembly 52 is described in more detail below.

FIG. 3 is a side view of filter assembly 52 with partial transparency toillustrate interior components according to aspects of the subjecttechnology. As depicted in FIG. 3, filter assembly 52 includes plenumbox 300 having an inlet 310, blower 320, baffle plate 330, filter panels340 and 345, and collector 350. Filter panels 340 and 345 may beaccessible via an access door in the side of plenum box 300 to replaceand/or clean the filter panels. The subject technology is not limited tothe specific arrangement and numbers of components depicted in FIG. 3.Other similar arrangements and different numbers of respectivecomponents may be used to perform the filtration processes described infurther detail below with respect to FIGS. 4 and 5.

FIG. 4 is a cross-sectioned perspective view of filter assembly 52according to aspects of the subject technology. FIG. 5 is a perspectiveview of filter assembly 52 according to aspects of the subjecttechnology. In the example depicted in FIG. 4, one side of plenum box300 is partially enclosed by collector 350 with inlet 310 creating anopening in collector 350. Inlet 310 is a coupling mechanism configuredto couple plenum box 300 to machine tool enclosure 40 to allow fluidcommunication between plenum box 300 and machine tool enclosure 40. Inthis manner, mist-laden air may be drawn into plenum box 300 from theinside of machine tool enclosure 40. When mounted on or within machinetool enclosure 40, collector 350 with inlet 310 may be arrangedgravitationally below baffle plate 330 and filter panels 340 and 345. Inthis regard, being gravitationally below another component means that,for example, fluid that condenses or accumulates on a surface of baffleplate 330 or filter panels 340 and 345 will be drawn by gravity to fallinto collector 350. Collector 350 may be graded towards inlet 310,through which gravity will cause fluid that has fallen into collector350 to drain out via inlet 310 into machine tool enclosure 40.

According to aspects of the subject technology, collector 350 may beconfigured to return the fluid collected in collector 350 to machinetool enclosure 40 or directly into the storage tank of fluid deliverysystem 60. For example, collector 350 may be graded towards a portformed in collector 350 different from inlet 310. The port may becoupled in fluid communication with fluid delivery system 60 to allowthe collected fluid to be filtered and returned to the storage tank.

As further depicted in FIG. 4, plenum box 300 is also coupled in fluidcommunication with an inlet of blower 320. Blower 320 may be acentrifugal blower, such as a high velocity centrifugal blower. Blower320 is configured to draw mist laden air into plenum box 300 via inlet310 and exhaust the air after it passes through the filter panels 340and 345 within plenum box 300 and out via outlet 350 illustrated in FIG.5. For example, when an impeller within housing of blower 320 is spun, avacuum may be created at the inlet to blower 320, which draws air frommachine tool enclosure 40 through plenum box 300. Blower 320 may beoperated at the start of a cutting operation or after a predeterminedperiod of time following the start of a cutting operation. Blower 320may be run continuously during the cutting operation or intermittently.When run intermittently, blower 320 may be cycled on and off based on apredetermined interval or based on detected or inferred mistconcentration levels within machine tool enclosure 40. Blower 320 maycontinue to run after the end of a cutting operation to continue thefiltration process as described above.

As noted above, blower 320 may be a centrifugal blower. Centrifugalblade blowers may provide higher static pressure performance than othertypes of blowers or fans, which may improve the flow rate of the mistladen air being drawn into plenum box 300. The size and operating speedof blower 320 may be selected based on the volume of machine toolenclosure 40. For example, mist extraction system 50 may be designed toturn the air inside machine tool enclosure 40 a specified number ofturns per minute (e.g., one to four turns per minute). If the volume ofmachine tool enclosure 40 is between 100 and 400 cubic feet, a ½ hp (375watt) centrifugal blade blower may be selected for blower 320 to produceflow rates between 100 and 200 CFM.

Outlet 350 may be coupled to exhaust duct 54 shown in FIG. 2 to returnthe filtered air back into machine tool enclosure 40 via return register56. The dimensions of exhaust duct 54 may be selected to maintain a flowrate of the air traveling through the duct. If the flow rate is tooslow, condensation of any remaining mist droplets may occur on thesurface of exhaust duct 54 which may result in stagnant pools of thecutting fluid accumulating within exhaust duct 54. For the examplesystem noted above having a blower producing flow rates between 100 and200 CFM, the diameter of exhaust duct 54 may range between 3 inches and8 inches, with better performance having been noted in the range between4 inches and 5 inches.

The arrows illustrated in FIG. 4 depict an example airflow path ofmist-laden air drawn into plenum box 300 by blower 320. As themist-laden air is drawn in through inlet 310, the mist-laden aircollides with and is redirected by baffle plate 330. The mist dropletssuspended in the air are heavier than the air and collide with baffleplate 330 as the airflow path is redirected by baffle plate 320. Themist droplets collide and condense or coalesce on the surface of baffleplate 330 and begin to grow in mass. This phenomenon may be referred toas inertia impaction or inertial separation. The droplets attach andcollect in mass on baffle plate 330 as well as inlet 310 whereeventually gravity forces the droplets to drip downward against the airflow, back into machine tool enclosure 40 and eventually the storagetank of fluid delivery system 60. This collision and collection ofdroplets on baffle plate 330 represents a first stage of the filtrationprocess.

After being redirected by baffle plate 330 the airflow path of themist-laden air travels within plenum box 300 and is drawn through filterpanels 340 and 345 by blower 320. Filter panels 340 and 345 operate in asimilar manner to baffle plate 320. For example, the mist-laden airpasses through filter panels 340 and 345 forcing the air to changedirections multiple times and the air flows through the media of thefilter panel. The mist droplets suspended in the air collide with thefilter media and condense or coalesce on the filter media. As thedroplets attached and collect in mass on the filter media, gravityforces the droplets to drain downward through filter panels 340 and 345toward and eventually into collector 350.

The filtering process does not rely on filter panels 340 and 345 toremove all mist droplets from the air in a single pass through thefilter media. Accordingly, more coarse filter media may be used forfilter panels 340 and 345. For example, the filter media may perform asieving type of filtration wherein relatively large particles ordroplets may be passable through the filter media. In certain aspects ofthe subject technology, the pore size of the filter media may filter outparticle or droplets 10 microns or larger but may allow particles ordroplets smaller than 10 microns to pass through the filter media. Thesubject technology is not limited to pore sizes of this dimension andmay use filter media with different pore sizes. While it is possible fordroplets smaller than the pore size of the filter media to pass through,some of those droplets will collide with the filter media and condenseor coalesce on the filter media rather than passing through. Thisstripping out of mist droplets by filter panels 340 and 345 represents asecond stage of the filtration process.

The more coarse filter media may provide both cost and maintenanceadvantages over more fine filter media that may be relied upon in othersolutions to filter out the droplets in a single pass. The more coarsefilter media may be less likely to clog and therefore require lessfrequent cleaning or replacement. The filter media may be one of severaltypes of filter media including spun metal, polyester, polyethylene, ornano-filtration media specific to the type of cutting fluid being usedin the machine tool. In the case of applications dry cutting wood, foamor other dust generating material, the filter panels could be swappedout for paper or fiber filter media. Filter panels 340 and 345 maycomprise the same type of filter media or different respective types andsizes of filter media according to aspects of the subject technology.While two filter panels are depicted in FIGS. 3 and 4, the subjecttechnology may be practiced with a single filter panel or with more thantwo filter panels.

After passing through filter panels 340 and 345, the mist-laden airenters blower 320 and is exhausted out of blower 320 via outlet 360.While in blower 320, the mist-laden air impacts impeller blades andinterior surfaces of the housing of blower 320. Similar to baffle plate330 and filter panels 340 and 345, droplets remaining in the air maycoalesce, collect and drain from those surfaces through a drain port inthe housing of blower 320 and into collector 350. The removal of mistdroplets within blower 320 represents a third stage of the filtrationprocess.

As discussed above with respect to FIG. 2, the air filtered by filterassembly 52 is exhausted back into machine tool enclosure 40 via exhaustduct 54 and return register 56. The filtered air may contain additionalmist droplets that may be stripped out after another pass through filterassembly 52. As depicted in FIG. 2, filter assembly 52 is coupled tomachine tool enclosure 40 near a first end of the enclosure while returnregister 56 is arranged to discharge the filtered air at a second end ofthe enclosure opposite the first end. As in the depicted example, inlet310 of filter assembly 52 and return register 56 are coupled todifferent sides of machine tool enclosure 40 and arranged on therespective sides at opposite ends of machine tool enclosure 40. Returnregister 56 may be arranged inside of machine tool enclosure 40, asdepicted, or outside of machine tool enclosure 40 with an opening intomachine tool enclosure 40 to allow the return of the filtered air.

FIGS. 6A and 6B depict return register 56 according to aspects of thesubject technology. As depicted, return register 56 includes a registerbody 600, an intake port 610, and an outlet register 620. Intake port610 may be coupled to exhaust duct 54 to receive the filtered airexhausted from filter assembly 52. A breather may be incorporated intointake port 610 to allow some of the filtered air exhausted by filterassembly 52 to escape. The filtered air may be pressurized by blower 320and without the breather allowing some of that filtered air to escape,the pressurized filtered air may cause mist-laden air to be pushed outof machine tool enclosure 40 through cracks or other small openings inthe enclosure. The escape of the mist-laden air may expose people inproximity to machine tool 10 to the harmful mist and may result incutting fluid collecting and weeping down the sides of machine toolenclosure 40.

As illustrated in FIG. 6B, the interior of register body 600 and outletregister 620 may be configured to diffuse the filtered air prior toreturning the air to machine tool enclosure 40. The diffused air maycreate a column of air that moves across machine tool enclosure 40 fromthe end where return register 56 is coupled to machine tool enclosure 40to the end where filter assembly 52 is coupled to machine tool enclosure40. This column of air may push mist-laden air in its path towards inlet310 of filter assembly 52 to be drawn into filter assembly 52 forfiltration. The recirculation of the filtered air that may reenterfilter assembly 52 along with new mist-laden air represents a fourthstage of the filtration process.

A reference to an element in the singular is not intended to mean oneand only one unless specifically so stated, but rather one or more. Forexample, “a” module may refer to one or more modules. An elementproceeded by “a,” “an,” “the,” or “said” does not, without furtherconstraints, preclude the existence of additional same elements.

Headings and subheadings, if any, are used for convenience only and donot limit the invention. The word exemplary is used to mean serving asan example or illustration. To the extent that the term include, have,or the like is used, such term is intended to be inclusive in a mannersimilar to the term comprise as comprise is interpreted when employed asa transitional word in a claim. Relational terms such as first andsecond and the like may be used to distinguish one entity or action fromanother without necessarily requiring or implying any actual suchrelationship or order between such entities or actions.

Phrases such as an aspect, the aspect, another aspect, some aspects, oneor more aspects, an implementation, the implementation, anotherimplementation, some implementations, one or more implementations, anembodiment, the embodiment, another embodiment, some embodiments, one ormore embodiments, a configuration, the configuration, anotherconfiguration, some configurations, one or more configurations, thesubject technology, the disclosure, the present disclosure, othervariations thereof and alike are for convenience and do not imply that adisclosure relating to such phrase(s) is essential to the subjecttechnology or that such disclosure applies to all configurations of thesubject technology. A disclosure relating to such phrase(s) may apply toall configurations, or one or more configurations. A disclosure relatingto such phrase(s) may provide one or more examples. A phrase such as anaspect or some aspects may refer to one or more aspects and vice versa,and this applies similarly to other foregoing phrases.

A phrase “at least one of” preceding a series of items, with the terms“and” or “or” to separate any of the items, modifies the list as awhole, rather than each member of the list. The phrase “at least one of”does not require selection of at least one item; rather, the phraseallows a meaning that includes at least one of any one of the items,and/or at least one of any combination of the items, and/or at least oneof each of the items. By way of example, each of the phrases “at leastone of A, B, and C” or “at least one of A, B, or C” refers to only A,only B, or only C; any combination of A, B, and C; and/or at least oneof each of A, B, and C.

It is understood that the specific order or hierarchy of steps,operations, or processes disclosed is an illustration of exemplaryapproaches. Unless explicitly stated otherwise, it is understood thatthe specific order or hierarchy of steps, operations, or processes maybe performed in different order. Some of the steps, operations, orprocesses may be performed simultaneously. The accompanying methodclaims, if any, present elements of the various steps, operations orprocesses in a sample order, and are not meant to be limited to thespecific order or hierarchy presented. These may be performed in serial,linearly, in parallel or in different order. It should be understoodthat the described instructions, operations, and systems can generallybe integrated together in a single software/hardware product or packagedinto multiple software/hardware products.

In one aspect, a term coupled or the like may refer to being directlycoupled. In another aspect, a term coupled or the like may refer tobeing indirectly coupled.

Terms such as top, bottom, front, rear, side, horizontal, vertical, andthe like refer to an arbitrary frame of reference, rather than to theordinary gravitational frame of reference. Thus, such a term may extendupwardly, downwardly, diagonally, or horizontally in a gravitationalframe of reference.

The disclosure is provided to enable any person skilled in the art topractice the various aspects described herein. In some instances,well-known structures and components are shown in block diagram form inorder to avoid obscuring the concepts of the subject technology. Thedisclosure provides various examples of the subject technology, and thesubject technology is not limited to these examples. Variousmodifications to these aspects will be readily apparent to those skilledin the art, and the principles described herein may be applied to otheraspects.

All structural and functional equivalents to the elements of the variousaspects described throughout the disclosure that are known or later cometo be known to those of ordinary skill in the art are expresslyincorporated herein by reference and are intended to be encompassed bythe claims. Moreover, nothing disclosed herein is intended to bededicated to the public regardless of whether such disclosure isexplicitly recited in the claims. No claim element is to be construedunder the provisions of 35 U.S.C. §112, sixth paragraph, unless theelement is expressly recited using the phrase “means for” or, in thecase of a method claim, the element is recited using the phrase “stepfor”.

The title, background, brief description of the drawings, abstract, anddrawings are hereby incorporated into the disclosure and are provided asillustrative examples of the disclosure, not as restrictivedescriptions. It is submitted with the understanding that they will notbe used to limit the scope or meaning of the claims. In addition, in thedetailed description, it can be seen that the description providesillustrative examples and the various features are grouped together invarious implementations for the purpose of streamlining the disclosure.The method of disclosure is not to be interpreted as reflecting anintention that the claimed subject matter requires more features thanare expressly recited in each claim. Rather, as the claims reflect,inventive subject matter lies in less than all features of a singledisclosed configuration or operation. The claims are hereby incorporatedinto the detailed description, with each claim standing on its own as aseparately claimed subject matter.

The claims are not intended to be limited to the aspects describedherein, but are to be accorded the full scope consistent with thelanguage of the claims and to encompass all legal equivalents.Notwithstanding, none of the claims are intended to embrace subjectmatter that fails to satisfy the requirements of the applicable patentlaw, nor should they be interpreted in such a way.

What is claimed is:
 1. A mist extraction system, comprising: a plenumbox comprising an inlet configured to be coupled in fluid communicationwith a machine tool enclosure; a blower coupled in fluid communicationwith the plenum box and configured to draw air into the plenum box fromthe machine tool enclosure via the inlet of the plenum box and exhaustthe air back into the machine tool enclosure via an outlet of theblower; a baffle plate arranged in the plenum box to redirect the airdrawn into the plenum box; a filter panel arranged in the plenum box tofilter the air redirected by the baffle plate prior to the air enteringthe blower, wherein the inlet of the plenum box is gravitationally belowthe baffle plate and the filter panel; and a collector arranged tocollect mist from the air condensed on the baffle plate and the filterpanel.